iOS 11.4 (build 15F5079a) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-05-17T17:02:31Z. The update package is 276.39 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 355fcbc55dc14b0aa76d8d7ff9e98335bf6aa522.zip.